Oil return in refrigerator



Filed sept. 9, 1949 Condenser INVENTOR `JOHN Bosl ATTORNEY Patented Sept. 25, 1951 UNITED STATES PATENT OFFICE OIL RETURN IN REFRIGERATOR John Bosi, Philadelphia, Pa.

Application September 9,-1949, Serial No. 114,898

2 claim. rc1; 62-s) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) l This application is made under the act of March 3, 1883, as amended by the act of April 30, 1928, and the invention herein described,-

if patented in any country, may be manufactured and used by or for the Government of the United States of America for governmental purposes throughout the world without the payment to me of any royalty thereon.

This invention relates to refrigerators and especially to one provided with an oil-lubricated compressor and a condenser for liquifying a gaseous refrigerant, and with a heat .exchanger in which the liquid refrigerant is evaporated, the gaseous refrigerant being recirculated to the compressor. Such a system usually employs a float-operated valve in the liquid line leading from the condenser to the heat exchanger for regulating the amount of liquid refrigerant contained in the exchanger, and has means, such as a constant pressure regulator valve, in the suction line leading from the heat exchanger to the compressor for maintaining a constant pressure on the liquid refrigerant boiling in the heat exchanger, thus to regulate the temperature.

Conventionally, the compressor of such a system contains lubricating oil of greater specific gravity than the liquid refrigerant. During operation the oil tends to form a mist part of which becomes entrained with the refrigerant, and is carried over into the heat exchanger. An oil separator for separating the liquid droplets of oil from the gaseous refrigerant may be located in the line between the compressor and condenser. Generally, such a separator is not sufficiently efficient to effect complete separation. In this case some liquid oil is gradually removed from the compressor and collects in the bottom lof the heat exchanger as a layer, the liquid refrigerant layer being suspended thereon. This lowers the efficiency of the exchanger, especially if the bottom coils for circulating the liquid coolant becomes buried in the oil. Also, the removal of oil from the compressor may result in destruction of the compressor due to faulty lubrication if the oil is not replaced.

When in a system of this type the heat exchanger becomes oil loaded, it is necessary to shut down and clean the system. This is time consuming and expensive.

It is the object of the present invention to modify or add to such a system so as to provide means which conveniently transfer oil collected in the exchanger back to the compressor.

In general. according to the invention, a tube containing a regulating valve for controlling the fluid ow therethrough is provided, the tube communicating at one end with the heat exchanger near the bottom thereof, and at the other end with the suction line between the means for maintaining constant pressure and the compressor.

Since the pressure is less in the suction line than in the exchanger, any oil collected in the bottom of the exchanger will flow through the tube into the suction line and thus be directly returned to the compressor, provided of course that the fluid flow regulating valve is open. This valve is preferably a hand regulated valve. such as a needle valve, for precise adjustment. If

the valve is opened more than necessary to pass the oil as it collects, the liquid refrigerant will also Iiow through the tube and be evaporated in the tube beyond the valve. This chills the tube. If on the other hand the valve is not sufficiently opened to pass all the oil, only oil will flow therethrough, in which case the tube is not chilled. Thus, thevalve may be adjusted to pass all the oil and a very small amount of liquid refrigerant, simply by observing the temperature of the portion of the tube just beyond the valve, as by sweating of the tube due to chilling. The valve should be set so that sweating occurs for a slight distance beyond the valve.

The valve may also be automatically regulated as by a thermostat responsive to temperature changes in the tube beyond the valve, operating to close the valve when cooled due to passage of the liquid refrigerant and to open the valve when warmed and maintain it open so long as only oil flows. With such automatic regulation the valve opens and closes intermittently, the period of intermittency being determined by how closely the valve is set in its opened position to pass only the collected oil.

For a more detailed description of the invention, reference is made to the accompanying drawing, in which- Figure I is a diagram, old parts being shown in dotted lines and the improvement of the present invention in full lines; and

Figure 1I is a similar diagram of a modified form.

In Figure I of the drawing, I is the heat exchanger, 2 the liquid line leading from the condenser and its receiver to the heat exchanger. 3 the float-operated valve in the liquid line, 4 the oat for operating the valve, and 5 the constant pressure regulator valve in the suction line 6 leading from the heat exchanger to the compressor. the compressor, condenser, receiver and oil separator previously mentioned being shown with appropriate legends. The coils for circulation of the liquid coolant through the heat exchanger are illustrated at 1.

The parts above described are conventional. According to the present invention, tube l is added shown in Figure I passing through the top ot the heat exchanger and communicating at one end with the heat exchanger near its bottom so that oil in the bottom of the exchanger enters the tube. At its other end, the tube communicates with the suction line 6 at a point between constant pressure valve 5 and the compressor. S'

illustrates the regulating valve in the tube 8, and I0 the thermostat for regulating the valve.

The modication illustrated in Figure II is similar except that the tube 8 does not pass through the top of the heat exchanger but is installed entirely outside thereof, communicating with an aperture in the bottom of the exchanger.

I claim:

1. In a refrigerator having an oil-lubrcated compressor and a condenser for llquifying a gaseous refrigerant, a heat exchanger in which the liquiiled refrigerant is evaporated. a suction line leading from the heat exchanger to the compressor, and means il. the suction line for maintaining a constant pressure on the refrigerant in the heat exchanger, means for transferring oil co1- lected in the exchanger back to the compressor comprising a tube communicating at one end with the heat exchanger near the bottom thereof and at the other end with the suction line between the means for maintaining constant pressure and the,compressor, said tube having a regulating valve therein remote from the compressor for controlling the fluid flow through the tube.

2. The subject matter of claim 1 in which the regulating valve is regulated by a thermostat responsive to temperature changes in the tube beyond the valve.

JOI-IN BOSI.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number 

